Industrial processes frequently contribute to cyanide ion contamination of ground and surface water. Such contamination is a critical problem in drinking water and cyanide ion is toxic to aquatic species in surface water. There is a great need for a more reliable and accurate method for determining levels of cyanide in environmental fluids. Classical methods usually involve acidification of an analytical sample to form HCN and distillation procedures to obtain separation. Such methods are generally unreliable due to sulfides which may be present in sample solutions and which form thiocyanate and H.sub.2 S interferences in analytical determinations. Tanaka, Analytica Chimica Acta, 214, 259-269, 1988, described an alternate procedure using microporous permeation membranes to provide more selectivity for cyanide by flow-injection analysis. One area where cyanide is used on a large scale is in the commercial recovery of gold from low grade ores and a representative reference includes: "Processing Gold Ores using Leach-Carbon Adsorption Methods", Information Circular, Bureau of Mines--No. 8770, 1978.
Currently a good deal of interest has been generated in the analytical community in particle loaded membrane technology and its applications for solid phase extractions as discussed by Hagen et al. "Membrane Approach to Solid Phase Extractions" Analytica Chimica Acta, 236, 157-164,1990. and by Markell et al. "New Technologies in Solid Phase Extraction" LC/GC Volume 9, Number 5, 1991. This technology has been shown to be useful for isolation of hydrophobic organic pollutants by adsorptive interactions and has demonstrated the advantages of fast diffusion kinetics when small, high surface area particles are packed closely together in uniform membranes with little or no channeling and controlled porosity. Van Osch et al. have described a membrane (i.e., a "pellet impervious to a solution of ions) for ion electrodes, Z. Anal. Chem. 271-4, 1975. These solid "membranes" disclosed in U.S. Pat. No. 3,824,169 are imporous (non-porous), chemically inert, composites of gold and salts pressed into pellets which are used in potentiometric electrode technology. These solid "membranes" should not be confused with the porous particle loaded articles disclosed in U.S. Pat. Nos. 4,153,661, 4,460,642, 4,810,381, 4,906,378, 4,971,736, 5,019,232, 5,071,610, and 5,147,539 for applications in separation science utilizing solid phase extractions.
Particle-loaded, non-woven, fibrous articles wherein the non-woven fibrous web can be compressed, fused, melt-extruded, air-laid, spunbonded, mechanically pressed, or derived from phase separation processes have been disclosed as useful in separation science. Sheet products of non-woven webs having dispersed therein sorbent particulate have been disclosed to be useful as, for example, respirators, protective garments, fluid-retaining articles, wipes for oil and/or water, and chromatographic and separation articles. Coated, inorganic oxide particles have also been enmeshed in such webs.